ARS | Publication request: Reactive oxygen species trigger a regulatory module invovled in the early responses of rice seedlings to cold stress

Submitted to: Biomed Central (BMC) Genomics
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: June 18, 2007
Publication Date: June 18, 2007
Citation: Chen, C., Yun, K., Ressom, H., Mohanty, B., Bajic, V.B., Jia, Y., Yun, S., De Los Reyes, B.G. 2007. Reactive oxygen species trigger a regulatory module involved in the early responses of rice seedlings to cold stress. Biomed Central (BMC) Genomics. 18:175.

Interpretive Summary: Major regulatory pathways in plants that evolved to withstand freezing by cold acclimation have been elucidated in Arabidopsis. We used rice to study that plants respond to low temperature through an intricately coordinated transcriptional network controlled by specific groups of transcription factors. A prominent pathway known in Arabidopsis is the CBF/DREB regulon, which was also shown to be evolutionarily conserved between temperate and warm-season plants. Our study exploited the wide contrast in chilling tolerance between indica and japonica rice as model to dissect the hierarchical organization of early response gene regulon by integrative analysis of promoter architecture and gene expression profiles. Analysis of the transcriptome of japonica rice identified a group of genes that were up regulated during the initial 24 hours at 10C. Included two transcription factors (ROS-bZIP1, OsMyb4) were among the 120 ‘early response’ genes were and another larger sub-group with a common denominator of having the as1/ocs element in their promoters. ROS-bZIP1, OsMyb4 and the as1/ocs element-containing genes were also induced by exogenous H2O2 at ambient temperature, thus are likely components of a regulatory module (ROS-bZIP1-as1/ocs regulatory module) that is activated by elevated intracellular ROS induced by cold stress. Comparative analysis of the expression of ROS-bZIP1-as1/ocs regulatory module between tolerant (CT6748-8-CA-17) and intolerant (INIAP12) rice cultivars showed positive correlation of the activity of the regulon with genotypic differences in chilling tolerance. We developed a hypothetical model of a gene regulon in rice mediated by ROS. It was hypothesized that the putative ROSbZIP1-as1/ocs regulatory module has a prominent role in configuring early or rapid responses to chilling in rice seedlings and that it is independent of the CBF/DREB-mediated and ABA-mediated regulons. Continued investigation will likely yield useful knowledge for the development of rice cultivars that are tolerant to low temperature.

Technical Abstract: Plants respond to low temperature through an intricately coordinated transcriptional network controlled by specific groups of transcription factors. Major regulatory pathways in plants that evolved to withstand freezing by cold acclimation have been elucidated in Arabidopsis. A prominent pathway is the CBF/DREB regulon that is evolutionarily conserved between temperate and warm-season plants. This study exploited the wide contrast in chilling tolerance between indica and japonica rice as model to dissect the hierarchical organization of early response gene regulon by integrative analysis of promoter architecture and gene expression profiles. Analysis of the transcriptome of japonica rice identified a group of genes that were upregulated during the initial 24 hours at 10oC. Included two transcription factors (ROS-bZIP1, OsMyb4) were among the 120 ‘early response’ genes were and another larger sub-group with a common denominator of having the as1/ocs element in their promoters. ROS-bZIP1, OsMyb4 and the as1/ocs element-containing genes were also induced by exogenous H2O2 at ambient temperature, thus are likely components of a regulatory module (ROS-bZIP1-as1/ocs regulatory module) that is activated by elevated intracellular ROS induced by cold stress. Comparative analysis of the expression of ROS-bZIP1-as1/ocs regulatory module between tolerant (CT6748-8-CA-17) and intolerant (INIAP12) rice cultivars showed positive correlation of the activity of the regulon with genotypic differences in chilling tolerance. A hypothetical model of a gene regulon in rice mediated by ROS was developed. It was hypothesized that the putative ROSbZIP1-as1/ocs regulatory module has a prominent role in configuring early or rapid responses to chilling in rice seedlings and that it is independent of the CBF/DREB-mediated and ABA-mediated regulons.